Vertebroplasty is a well-known procedure for augmenting a vertebrae that has collapsed due to osteoporosis or other indication. See, for example, U.S. Pat. No. 6,273,916 to Murphy (“Murphy #1”) and issued Aug. 14, 2001, the contents of which are incorporated herein by reference. In general terms, vertebroplasty involves transpedicular or posterolateral injection of a bone cement into the vertebral body.
As is described in Murphy #1 and elsewhere, various types of bone cements can be used. One common bone cement is polymethylmethacrylate, but other types will occur to those of skill in the art. A common feature of many bone cements, is that they have a viscosity such that substantial pressure can be required to effect expression of the bone cement from the syringe, through any connective tubing and the needle and into the vertebral cavity. However, also as described in Murphy #1, considerable care is required to reduce the likelihood of overfilling the vertebral body, as such overfilling can rupture the spinal cord and paralyze the patient. Prior art syringes, connecting tubes and needles, however, can in some circumstances impede controlled and careful injection of bone cement into the vertebral body due to irregularities found along the channel between the syringe body and the needle tip. Such irregularities can be found, in particular examples of prior art, at luer-lock junctions for removable connections between the syringe, the connecting tube and the needle. Further viscosities of non-polymethylmethacrylate cements are generally greater than the viscosity of polymethylmethacrylate's, and such viscosities can present problems at luer-lock junctions.
Additionally, because vertebroplasty is performed under image-guidance, extra care may be taken to reduce the radiologist's (or other medical professional performing the procedure) exposure to the imaging beam under which the procedure is performed. Thus, U.S. Pat. No. 6,488,667 to Murphy (“Murphy #2”) teaches a needle holder that can be used to allow the radiologist to grasp and control the needle during insertion into the vertebral body, while also allowing the radiologist to keep his or her hands farther away from the imaging beam than if the radiologist had to grasp the needle directly. While effective, one problem, however, with the needle holder in Murphy #2 is that in certain circumstances, the needle holder can slide along the length of the needle, which can interfere with the desired level of control over the needle.